Sound-absorbing materials are desirable in various vehicles and facilities with people present because exposure to high noise levels can cause hearing loss, increase stress, and interfere with communication. Some current types of noise dampening materials include active noise cancelling piezo-electric materials and passive foams and foam-like materials, but each has associated disadvantages. For example, weight and space are concerns for the passive foam materials, which are typically relatively heavy and voluminous. Heavy foam installed within certain vehicles, such as aircraft, may result in increased fuel consumption and reduced operating efficiency. Another disadvantage of passive foam materials is that the materials are typically not designed to absorb sound at frequency ranges of interest that are specific to a certain application. The piezo-based systems may be smaller and/or lighter than the foams, but require hardware, such as electrical components, circuitry, and power supplies. The piezo-based systems are generally more complex and costly to manufacture, install, operate, troubleshoot, and repair than the passive foams, and reliability of the systems can also be an issue.